Settings : Add country code to blacklist entry dialog

Enforce country code when adding an entry. If the user has regex enabled,
* is added to the list as a choice. This avoids the confusion users are currently
facing where blocking only the number + regex doesn't work, since country code is expected.

Eg :

206* won't work
+1206* works

CYNGNOS-3049
BACON-4953

Change-Id: I9236898f17fcef425e561aaa10e56c5e8c2171a7